The present invention relates to transition metal catalysts.
In the polymerization of alpha-olefins, it is known to use catalysts comprising a transition metal compound and an organometallic compound. It is further known that the productivity of such catalysts can generally be improved if the transition metal compound is employed in conjunction with a metal halide, such as MgCl.sub.2. The catalysts described above produce polymers of narrow molecular weight distribution (MWD) and do not exhibit a multimodal or broad molecular weight distribution.
For many applications, such as extrusion and molding processes, it is highly desirable to have polymers which have a broad molecular weight distribution of the unimodal or the multimodal type. Such polymers evidence excellent processability, i.e., they can be processed at a faster throughput rate with lower energy requirements with reduced melt flow perturbations.
It is also highly desirable to produce multimodal or broad molecular weight distribution polymers directly in a single reactor, without having to blend polymers having different molecular weights and distribution in order to obtain the advantages of this invention.